


Assumptions

by BG97



Category: Stray Kids (Band)
Genre: Alternate Universe - College/University, Anal Fingering, Anal Sex, Biting, Bottom Seo Changbin, Boys In Love, Boys Kissing, Committed Relationship, Cuddling & Snuggling, Hyung Kink, Inspired by Twitter, Light Dom/sub, M/M, Plot What Plot/Porn Without Plot, Public Display of Affection, Rimming, Rough Sex, Seungbin's Duality, Sort Of, Top Kim Seungmin, Wet & Messy
Language: English
Status: Completed
Published: 2019-10-17
Updated: 2019-10-17
Packaged: 2020-12-20 22:35:53
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,866
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21064316
Author URL: https://archiveofourown.org/users/BG97/pseuds/BG97
Summary: Jisung’s too-loud giggle sounded from somewhere over his shoulder, Seungmin just groaned, trying to nuzzle deeper into Changbin’s chest, “Seriously though, hyung’s the only person that can keep Seungmin in line.”Seungmin should be annoyed, but he couldn't help the smile that tugged on the corners of his lips at the irony, shifting so he could look up at his boyfriend with wide eyes. "Really, what would anyone do if I didn't have Changbin hyung to keep me in line?"Alternatively: Everyone likes to make assumptions about Seungmin and Changbin.For the prompt: Seungbin soft cuddles and hand holding in the streets but rough and dirty in the sheets.





	Assumptions

**Author's Note:**

> Welcome!
> 
> So, this is my first time writing seungbin and also my first time messing around with title kinks, I hope I didn't horribly fail at either.
> 
> This was originally meant to be a drabble, but it turned into a Twitter thread, but the word count got too high so now it's going on here. You're welcome!
> 
> This was not thoroughly edited so I apologize for any silly mistakes <3
> 
> But I hope everyone enjoys!

Seungmin was in a bad mood.

The campus coffee shop was randomly closed this morning, and if there's anything worse than walking to class at 7:45am, it's the jarring sensation of trying to yank open a door you didn't expect to be locked, industry-grade espresso machine gleaming in the early morning sun, abandoned in the empty building. He could practically hear it crying out for him through the window, just begging to give him his daily americano… but maybe that was just the impending caffeine-withdrawal headache already brewing at the front of his skull.

_ So _ , Seungmin walked into his 8am  _ empty handed _ for the first time that semester, only to discover that Jisung decided to skip their presentation that morning. Didn't even bother texting him a heads-up until fifteen minutes into class,  _ after  _ Seungmin blew his phone up demanding to know where he was.

And maybe that'd have been fine… if Jisung had actually sent him the finished version of their visual aid so Seungmin wouldn't have to rush to throw something together while other groups presented, still  _ decidedly uncaffeinated _ .

So, Seungmin was in a bad mood; the kind of bad mood where there's very,  _ very  _ few things that could possibly turn it around...

Thank god for Changbin.

Honestly, Seungmin could have cried at the sight of his boyfriend standing outside the lecture room at 9:30am on the one day he doesn't have classes with an overpriced Starbucks iced americano in his hands.

He settled for kissing him instead.

Felix and Hyunjin whined from somewhere behind them, but he couldn't really care when he could taste the toothpaste lingering on Changbin's lips, and when his boyfriend's still sleep-messy hair felt so nice and soft between his fingers. It was Changbin that broke the kiss, giggling as he simultaneously pressed the stupid expensive drink into his hands and a sweet peck to his cheek.

They walked hand in hand to the student union where Seungmin, Felix, Hyunjin, and Jisung usually killed time before their 11:40 classes, Changbin holding the conversation with their friends while Seungmin chugged his drink in record time.

He barely let his boyfriend sit down before he started making himself comfortable in his lap, Changbin giggling as Seungmin wormed around until he was satisfied with their positions, again ignoring the teasing complaints Hyunjin and Felix expressed at their overt public displays of affection. 

He'd gotten good at that since he started dating Changbin.

"I'm going to murder Jisung next time I see him."

"You don't mean that," Felix laughed, "besides, your presentation was still better than ours."

Hyunjin hummed in agreement around the muffin he'd snagged from the dining hall, "Plus, he told the group chat he was with Minho last night, everyone else knew he wasn't gonna make it to his classes today-"

Felix shoved his shoulder, "Not helping! We're trying to keep Jisung alive, remember? We like Jisung-"

Hyunjin flicked the crumbs from his muffin at Felix in retaliation and the two of them quickly dissolved into bickering and laughter.

Seungmin sighed, blocking them out, reclining back against Changbin's chest, fingers tracing along the toned muscles of his boyfriend's forearms, feeling the way they flexed as they wrapped tighter around his waist. The boy underneath him nuzzled his face gently into his neck, and Seungmin let his eyes slip closed as he leant into the older man's touch, "Do you know how to hide a dead body, hyung?"

Changbin hummed against his shoulder, "I'm sure we could figure something out."

Seungmin nodded in agreement, pressing a satisfied kiss to Changbin's soft hair. At least one person always had his back.

"That's, uhm… cute? I guess?"

Seungmin peaked through his eyelids at the other boys in time to catch Felix rolling his eyes in mock annoyance, "Seungmin and Changbin can make anything look cute, even premeditated murder."

Seungmin grinned despite himself, mood slowly improving, but it was hard not to feel good when Changbin was giggling softly against his neck, chest vibrating against his back, "We know."

“Hey guys!”

Seungmin has never gone from zero to one hundred so fast, but right as he’s about to throttle Jisung, Changbin’s arms lock around his waist, keeping him trapped against his body.

The utter betrayal on his face as he twists around to gape at his boyfriend… and their friends have the gall to laugh, “Traitor! I thought we were on the same page!”

Changbin tried to hide his giggle in Seungmin’s shoulder, but it didn’t quite work. The audacity. “I can’t let you murder him, babe; I’d barely get to see you if you went to prison-”

“No, the agreement was that you help me murder him and then we’re  _ both _ in prison so your argument is invalid.”

“I don’t think that’s how it works, and I’d still prefer you right here, so we have to keep him alive, for now.”

“For now?!” Felix and Hyunjin were practically hysterical, on the opposite couch, Jisung looking around with that stupid wide-eyed, innocent expression as if he didn't know  _ exactly _ why Seungmin was going to murder him horrifically in the middle of the bustling student union.

"I swear to god, if Professor Byun gives you anything over a zero for the presentation, you're dead to me."

Jisung looked offended, "I did half of the PowerPoint, why should I get a zero?!"

Felix smacked Jisung’s hip and even Hyunjin looked between the two of them alarmed; Changbin’s stupid strong arms tightened even further around his waist as if he could sense Seungmin’s impending blow-up.

But, no, Seungmin was totally fine, absolutely, one-hundred percent  _ fine _ . “You finished the PowerPoint?”

Jisung had the decency to look nervous at Seungmin’s cool tone. “... Yes?”

“Oh, cool, that’s good to know since you  _ didn’t send it to me _ .”

The dawning look of horrified realization on Jisung’s face was almost satisfying. Almost.

“I forgot! Oh my god, Seung, listen-”

“I’m sure it was just a mistake, babe,” Changbin spoke softly, pressing a gentle kiss to the space behind his ear, thumb rubbing up and down where it rested at Seungmin’s side. “Right, Jisung?”

Jisung pouted overdramatically, nodding his head hard enough to make his unstyled hair flop around his face.

Seungmin rolled his eyes, deciding it wasn’t worth it. He shifted in his boyfriend’s tight grip so he could sit side-ways across his lap, curling into his toned chest. “Whatever.”

“God, what would we do without Changbin hyung?” Seungmin considered finding something to throw at Hyunjin, but he was just too comfy. One of Changbin’s hands had come up to brush through his hair after the eminent danger passed and it just felt way too nice to move. Even after the coffee, he just felt drained and sleepy.

"Seungmin would've killed us all ages ago," Felix laughed, "we owe Changbin hyung our lives."

Jisung’s too-loud giggle sounded from somewhere over his shoulder, Seungmin just groaned, trying to nuzzle deeper into Changbin’s chest, “Seriously though, hyung’s the only person that can keep Seungmin in line.”

Seungmin should be annoyed, but he couldn't help the smile that tugged on the corners of his lips at the irony, shifting so he could look up at his boyfriend with wide eyes. "Really, what would anyone do if I didn't have Changbin hyung to keep me in line?"

Changbin's laugh was bright and innocent, but Seungmin didn't miss the way his hands gripped at him just a bit tighter.

Seungmin relaxed back into his chest, already thinking that it was going to be an awfully long day before he could get his boyfriend alone.

oOo

Seungmin didn't always appreciate the fact that Changbin lived off campus; it made plenty of normal boyfriend things more complicated and inconvenient, but…

It had its perks.

It's not like they could do  _ this _ in the dorm room Seungmin shared with three other people.

“Did you clean yourself out for me, baby?” Changbin whined so cutely into the sheets, squirming in embarrassment as Seungmin’s hands gripped at his toned ass, kneading and massaging into the muscles there.

God, he loved his boyfriend’s ass.

He loved how it fit just perfectly in his hands, how the firm flesh indented just right under his fingertips, the skin going pale as he pressed harder into the little Seungmin-made dimples, fading back into the gorgeous, rich tone of Changbin’s skin when he let go…

It was a great ass.

“What was that, sweetheart?” He bent down, breathing the words into the sensitive skin at the base of Changbin’s back before pressing a soft kiss there. Changbin gasped as Seungmin’s tongue lightly slid across his skin, tracing the space between the two adorable dimples that sat just above his hips.

“I-” Changbin shuddered as Seungmin grazed his teeth over the curves of his muscular back. He just really loved his boyfriend’s body. “I d-did…”

Seungmin hummed as he slowly rolled his body back up into a sitting position, squeezing once more at the clenching muscles before swiftly striking at the smooth skin, feeling the sting on his palm, watching the way Changbin jumped, his body tensing as he let out a shocked little noise.

“I did, hyung!” Seungmin felt the smile curling at his lips as he leant back down to pepper his boy’s shoulders with kisses. Changbin’s voice got so whiney and squeaky when he was like this, so fucking cute. Seungmin’s big, tough, older boyfriend always dissolved into such a needy, squirmy, little mess when they were in bed.

Seungmin slowly dragged his body lower, drawing a line of sweet little kisses down the curve of Changbin’s spine, feeling the staggering deep breaths his boyfriend was taking, the not-so-subtle way his squirming was really just him grinding down into the sheets.

He pressed his lips to the little bump of Changbin’s tailbone, before adjusting so he could rest his body comfortably between his boyfriend’s spread thighs, leaning on his elbows so he was at the perfect height to nuzzle his cheek into the warm, soft swell of his ass, eliciting a little embarrassed noise from the older man.

Seungmin let his hands rest on the valley of Changbin’s lower back as he pressed an open mouthed kiss over the red patch of skin where his hand had connected just moments before, slowly licking and suckling against the sore spot. Changbin was trembling under him, wiggling lightly. Seungmin could almost see his flushed cheeks and bitten lips in his mind as he continued to work over the toned muscle at a leisurely pace.

He really,  _ really  _ loved getting Changbin all to himself like this.

He knew his boyfriend was trying not to get too worked up too quickly, but he couldn't help shifting his hips under Seungmin. The younger man could envision that, too; Changbin's red, aching cock leaking all over his bedspread, desperate for the attention Seungmin was denying it for now.

He liked being able to watch and feel his boyfriend's ass clenching and shifting under him as the older man got more and more impatient, his own dick painfully hard in his boxer-briefs, but a particularly noticeable jerk had him biting down roughly on the ass in front of him. Changbin's loud gasps echoed off the bedroom walls, even as Seungmin soothed over the quickly reddening mark with his lips and tongue. "Stay still for me, baby," he whispered softly into the slick skin.

Changbin buried his face further in his forearms, the muscles on his back rippling as he shifted and settled in. Seungmin pressed a final kiss to the angry teeth marks that had joined the other - new and fading - bruises on his boyfriend's ass before placing his hands firmly on each of Changbin's cheeks, pulling them apart to reveal his cute little hole.

Seungmin didn't give his boyfriend warning before leaning in to lick around the dark rim, fascinated by the way it clenched under his tongue in response. Changbin let out a soft, mortified noise, but he stayed still, strong body nearly vibrating with his efforts.

It always amazes him, how his strong, bulky boyfriend listened to him so well, let him control everything they did. He wondered if Changbin ever thought about how easy it would be for him to just flip Seungmin over and pin him down, how quickly he could overpower him if he wanted to.

But he never did; Changbin was always such a good boy for Seungmin.

The younger man dug his fingertips into the firm flesh under his hands, pressing his face forward, totally focused on how Changbin’s tight muscles slowly opened up around his tongue, the precious little noises his boyfriend was making as he worked, the ‘oh my god,  _ hyung _ ’s he was breathing into the goose-bumps on his arms.

Seungmin had never even considered eating ass before he met Changbin… but he hadn’t considered a lot of sexual situations before meeting Changbin. They like to joke that they corrupted each other, and Seungmin has absolutely no complaints. 

He’s already drooling a bit as he alternates between pressing his tongue as deep as it will go and teasing it around the sensitive opening, his palms pulling Changbin’s cheeks as far apart as they can. His boyfriend’s skin is so smooth and feels so good against his mouth, his tongue, he can’t even mind the spit coating his chin and upper-lip, making both of them so messy, so  _ filthy _ . He revels in it; how he can drop the clean-cut charade when it’s just the two of them, totally exposed, just enjoying the pleasure they can give to one another.

Seungmin sucks at Changbin’s sensitive rim, loving the way it makes his boyfriend jerk involuntarily, before pulling off with a slick pop, drawing another embarrassed keen from the older man below him. He takes a minute to enjoy the sight of Changbin’s shiny, puffy hole, twitching under his gaze. He presses a thumb slowly inside, careful not to move too fast as he pulls at the muscle, watching it gradually loosen and open up for him.

His other thumb gently massages at the rim, slowly pressing inside, too. Changbin moans into his forearms, hips twitching as Seungmin opens him up at an agonizing pace. “Hyung,  _ please _ .”

“Tell me what you want, Binnie.” Seungmin’s voice is breathy, his lips tingling and too slippery as he forms the words, eyes seeking out the bottle of lube Changbin keeps on his nightstand. He can’t help grinding his own hips forward into the mattress; he can feel himself leaking into his boxer-briefs, his cock begging for attention. Seungmin loves foreplay… until he doesn’t, when they both get themselves so riled up, waiting another second feels like torture.

“God, fuck, hyung,” Changbin whines as Seungmin’s thumbs press shallowly into his hole, stretching the muscle ever wider, “need you to fuck me.”

Seungmin curses as he carefully frees one of his hands to grab at the bottle, fumbling with the flip cap one-handed before upending it and letting the cool liquid trickle onto Changbin’s exposed rim. He groans at the way Changbin jumps at the temperature change, clenching down around his thumb, but he doesn’t waste any time in sliding his fingers through the slippery mess, pressing two inside.

Changbin’s hips squirm as he’s suddenly filled much deeper than before, a soft noise leaving his lips as Seungmin twists his fingers around, gradually beginning to scissor them, encouraging his boyfriend to open up even more for him. 

Seungmin sits up, kneeling between his boyfriend's thighs, pressing his free palm into the sheets to give himself better leverage as he works his fingers, slowly adding a third. It has an added benefit of improving his view, letting him fully take in the sight of his boyfriend's swollen hole opening up under his ministrations.

Changbin's given up on staying still, pressing his hips back onto Seungmin's hand and then forward to grind down onto the sheets. He's letting out a medley of cute little whines, and deep, raspy moans that have Seungmin's cock twitching where it's still trapped against his hip by his underwear.

Curiously, Seungmin stops his movements, letting his fingertips rest just inside of his boyfriend; it takes a moment, but Changbin doesn't disappoint, whining as he shifts his weight onto his knees and elbows and puts all of his energy into fucking himself backwards on his fingers.

Seungmin feels his jaw go slack as he watches, free hand coming up to grip at his dick through the damp fabric of his underwear, hips rocking forward against his palm. "Fuck, baby, that's right, make yourself feel good…"

"Minnie hyung-" Changbin gasps out, fisting at the sheets as he falls apart, " _ please _ ... need you."

And how the fuck is Seungmin supposed to say no to that?

Seungmin buries his fingers deep one last time before carefully removing them so he could use both hands to drag his underwear off as quickly as possible, finally freeing his aching dick. His hips twitch as he wraps his slippery hand around it, so worked up and sensitive it's hard for him to think clearly, but he manages to grab the bottle of lube that he'd definitely let leak all over Changbin's sheets with his free hand, making sure to liberally coat his length.

"Turn over for me, baby," he groans, patting Changbin's ass to encourage him. Seungmin caps the bottle when he discards it this time, sparing a second to lament the laundry they'd have to do later, but his thoughts are quickly brought back to the present and the gorgeous man underneath him.

Changbin is a mess, his body flushed and covered in a sweaty sheen, fringe sticking up in all directions, soft tummy rising and falling with his rapid breaths, toned thighs spread wide, his cock just as Seungmin envisioned it, red and shining with how much he'd been leaking. His boyfriend's defined muscles flex as he grabs his pillow, working it under his hips as he looked up at Seungmin with wide eyes.

Seungmin decided not to make either of them wait any longer.

The first slow press inside his boyfriend’s body had Seungmin’s eyes rolling back, soft gasps falling from his lips, fingernails leaving crescent shaped indents in Changbin’s hip. The older man let out a breathless moan, head falling back against the sheets as his tight hole swallows Seungmin’s cock like that’s exactly where it belonged. 

Seungmin gives them both a moment to catch their breaths, adjust, before he’s gripping Changbin’s waist with both hands, slowly dragging his cock out, eyes locked on where Changbin was clutching around him, like he was trying to suck him back in.  _ God _ .

When just the head rested inside, he slowly began pressing forward, a choked moan falling from his lips as he sank back into his boyfriend’s body, hips eventually pressing against the older man’s ass, as deep as he could possibly go into the familiar silken heat. Changbin let out a soft little noise as Seungmin ground his hips in, dark eyes blinking up at him, a hand clumsily clutching at his wrist.

“Does it feel good, baby?” Seungmin felt wrecked, and it was so hard to keep his pace steady and controlled as he slowly began to rock into his gorgeous boyfriend, taking in every little gasp and moan that left the older man’s plush lips, the way his stomach clenched and his dick leaked onto the little swell of his belly.

“Yeah, fuck,” Changbin bit his lip, eyebrows furrowing as he nodded, “more, please, hyung?”

Seungmin’s hips slammed forward at the request, the sharp sound reverberating through the room along with the deep moans they both let out. 

“Fuck, Binnie,” Seungmin groaned as his hips snapped forward progressively faster, fingers digging little bruises into Changbin’s waist, feeling the way his strong body shuddered and writhed under his palms, firm thighs squeezing around his hips as he pounded into the gorgeous man underneath him.

Seungmin’s pace grows brutal, the sounds of his boney hips slapping against Changbin’s plush ass filling the room. His boyfriend is  _ so _ good; his smooth, warm channel is clutching at him in all the best ways, his soft waist feels so nice in his grip, his little whimpers and groans going straight to Seungmin’s dick...

He’s not going to last long at all.

Seungmin presses deep, squeezing his eyes shut, before completely changing his rhythm, focusing on rolling his hips nice and deep into Changbin’s body. He leans forward, laying himself across his boyfriend’s plush abdomen, one hand coming up to fist in the other man’s soft hair, the second cupping his jaw as Seungmin crashes their lips together.

Changbin’s own arms wrap immediately around his thin body, dull, bitten-off fingernails dragging down his back as his boyfriend clings to him desperately.

The kiss is dirty, filthy, neither of them capable of sparing much thought for technique, but so  _ good _ at the same time. Their new position has Seungmin’s flat stomach grinding against Changbin’s weeping cock with every shift of his hips, and he can already feel how quickly it has his boyfriend falling apart in his hands. His lips are quivering against Seungmin’s own, desperate whimpers filling the room, hands clutching at him and holding him as close as possible… it’s intoxicating.

Seungmin breaks the kiss, pressing his thumb against Changbin’s full lips until his boyfriend sucks it in, moaning around the digit, eyes fluttering closed. Seungmin’s hips stutter, grip tightening on the older man’s hair.

He’s so fucking close.

Seungmin attaches his mouth to the side of his boyfriend’s neck, pressing his body as close as he can, losing himself in the dirty, slick noises of his cock fucking into Changbin’s lax, wet hole, the feeling of his flat chest sliding against his boyfriend’s muscular one, both of them slippery with their own sweat.

He’s almost startled when Changbin lets out a loud, high-pitched cry, his hips jerking between the two of them, muscles clenching like a vice around Seungmin as his cum leaks between their bodies. He wonders distantly if his boyfriend’s nails might have broken skin, but then Changbin goes completely lax, his arms dropping to his sides.

Seungmin is as careful as he can be when he pulls out, his hand quickly wrapping around his slicked cock, pumping furiously over it as he leans over Changbin’s blissed out body.

His orgasm hits him hard, his whole body tensing and shuddering as he adds to the mess on his boyfriend’s belly. Seungmin feels the energy drain from his limbs, but Changbin catches him, holding him close and safe.

They lay like that for a long time, uncaring of the mess between them. They mostly just cuddle, keeping their bodies wrapped up in one another, sharing a lazy kiss every so often.

“Thank you, hyung...” Seungmin murmurs sleepily into Changbin’s neck, “...so good...”

His boyfriend chuckled lightly, sending pleasant vibrations up into Seungmin’s chest, making him feel all warm and fuzzy. “Of course, Minnie, you always take such good care of me.”

Soft, plush lips pressed against Seungmin’s temple, drawing a contented hum from deep inside him as he nuzzles impossibly further into his hyung’s embrace.

Thank god for Changbin.

**Author's Note:**

> I hope you all enjoyed!
> 
> Comments and questions always appreciated, either on here, Twitter, or CuriousCat!
> 
> Twitter: [BenGene97](https://twitter.com/BenGene97)  
CC: [BG1997](https://curiouscat.me/BG1997)


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